The present invention relates generally to turbine generators and, more particularly, to a generator housing and base assembly for a turbine generator.
Turbine generators commonly include a generator having a stator which supplies the power, and a rotor supplied with DC current from an exciter and operatively associated with the stator. The stator is mounted in a generator housing. The rotor is rotationally driven by a turbine, which also forms part of the turbine generator.
Conventionally, the turbine and the generator are each bolted to a base. In particular, the base is provided with a plurality of openings, a lower part of the generator fitting within a generator opening and a lower part of the turbine fitting within a turbine opening. The generator and turbine are individually bolted to the base in their respective openings. The generator and turbine are also operatively coupled to each other, so that the turbine drives the rotor.
The base is generally formed by a plurality of transverse webs which define the openings and stiffen the regions between the openings, with plates being welded to the webs to form a box-like structure. The generator includes a housing similarly formed by a plurality of transverse webs which support the generator structure, the webs being welded to plates to form a box-like structure. The generator housing is then bolted to the base within the generator opening.
Various problems arise with such connection of the generator to the base. The desirability of reducing the amount of vibration in a turbine generator is well known. However, a corner-to-corner vibration of the base at certain operating frequencies of the generator causes the transmission of undesirable Structureborne vibration therefrom. Specifically, a flapping mode of vibration is detectable at a corner of the base adjacent the generator.
A stiffening structure may be added to the base. Such structure is generally added in the form of a first supporting gusset extending along the bottom of the base from the flapping corner of the generator opening to the flapping corner of the base, and a second supporting gusset extending along the bottom of the base from the flapping corner of the generator opening to the center of the generator opening. The second supporting gusset is secured to the bottom of the generator housing that fits within the generator opening. In addition, lumped masses may be installed at the corners of the base to detune the structure for a particular range of frequencies. However, such stiffening structure and lumped masses do not provide an efficient solution to vibration reduction. In addition, the stiffening structure and lumped masses increases the weight and size of the turbine generator.
Further, since the base and the generator housing are constructed independently of each other, the transverse webs of the base and the generator housing are generally not in alignment; that is, although the base and housing webs are parallel to each other, they are generally offset with respect to each other. The offset reduces continuity of the structure and produces a design which is capable of a less than optimum weight utilization.